pub fn dp_rec_mc(amount: u32) -> u32 {
    let coins = vec![100, 50, 30, 20, 10, 5, 2, 1];
    let mut amount = amount;
    let mut res = 0;
    for coin in coins {
        res += amount / coin;
        amount -= amount / coin * coin;
    }
    res
}
